Note the difference between the fat seal (above)
and the skinnier one (below).

As Weddell seal pups nurse from their moms, they develop thick blubber layers because of the high percentage of fat contained in the milk that they drink. We learned in the previous activity just how much fat seal pups take in, and how much we would have to eat to equal that amount. This thick fat layer, which will be 2 ½ inches thick when the pup is full-grown, serves to keep the pup warm, even the coldest and harshest of Antarctic conditions. Interestingly enough, not all marine mammals that live in cold water use blubber to insulate themselves. Sea otters and fur seals, have a dense coat of fur, and they blow air into their fur to trap a layer of air between their skin and the water. Their fur is so thick that no water can reach their skin. This way, their skin stays dry and warm. Penguins, a marine bird, also use this air layer trick in their dense feathers to keep their skin warm and dry even during the coldest blizzards. So, which kind of insulation works better? Let’s find out! For this activity, a water balloon full of hot water will be our marine mammal. How will our different insulators (blubber and fur) stand up to ice water and keep our balloon warm?

This activity will require approximately one to one-and-one-half hours to complete. All materials can be purchased at grocery or drug stores, and most materials can be shared among groups of students. See Activity for more details.



A Weddell seal mom looks deflated after transferring
much of her fat stores to her growing pup.


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